| What is a vector quantity? | A value with magnitude and direction. |
| What is a scalar quantity? | A value with magnitude only. |
| What is magnitude? | Size. |
| What are contact forces? | Forces between objects that are touching. |
| What are non-contact forces? | Forces between objects that are not touching. |
| What are examples of contact forces? | Friction, thrust, air resistance, tension, normal force, applied force and upthrust. |
| What are examples of non-contact forces? | Magnetic force, gravitational force, electrostatic force and nuclear force. |
| What is weight? | The gravitational force on all matter within an object (mass). It's measured in N (newtons) |
| What is mass? | The amount of matter within an object. It's measured in kg (kilograms) |
| What are examples of vector quantities? | Force, velocity, displacement, acceleration and momentum. |
| What are examplesof scalar quantities? | Speed, distance, mass, temperature and time. |
| What type of force is the sun and moon attracted to each other by? | Gravitational force. |
| What is the equation for weight? | Weight (N) = Mass (kg) × Gravitational field strength (N/kg) |
| What is the gravitational field strength of the Earth? | 9.8 N/kg |
| An apple has a mass of 100 g. Calculate its weight on Earth (g = 9.8 N/kg). | W = m × g
100 g = 0.1kg
0.1 × 9.8
= 0.98N |
| What is the equation for work done? | Work done (J) = Force (N) × Distance (m) |
| What is gravitational field strength measured in? | N/kg. |
| What is a force? | The interaction between physical objects through pushing, pulling or twisting. |
| What is elastic deformation? | When an object returns to its original state when the deforming force is removed. |
| What is inelastic deformation? | When an object doesn't return to its original state when the deforming force is removed. |
| What is hooke's law? | For an object to be elastic, the force and extension need to have a linear relationship and be directly proportional. |
| What is the equation for hookes law? | Force = spring constant × extension. |
| What is spring constant measured in? | N/m. |
| What is the limit of proportionality. | The point where the extension is no longer directly proportional to the force. |
| What is the limit of elasticity/ elastic limit? | When an object has gone past its limit of proportionality and will no longer return to its original state when the deforming force is removed. |
| What shows the spring constant in a force-extension graph? | The gradient. |
| What shows the elastic energy in a force-extension graph? | The area of the triangle (before the limit of proportionality). |
| What is the equation for elastic potential energgy? | Elastic potential energy (J) = ½ × spring constant (N/m) × extension² (m) |
| A spring has a spring constant, (k), of 3 N/m. It is stretched until it is extended by 50 cm. Calculate the elastic potential energy stored by the spring, assuming it is not stretched beyond the limit of proportionality. | Eₑ = ½ × k × e²
50 cm = 0.5m
½ × 3 × 0.5²
> ½ × 3 × 0.25
= 0.375 J |
| A spring is compressed by 0.15 m. It has a spring constant of 80 N/m. Calculate the elastic potential energy stored by the spring. | Eₑ = ½ × k × e²
½ × 80 × 0.15²
> ½ × 80 × 0.0225
= 0.9 J |
| What is the required practical? | How forces affect the extension of a spring. |
| What is elastic deformation? | When the force deforming an object is removed and it returns to its original state. |
| What is inelastic deformation? | When the force deforming an object is removed and it doesn't return to its original state. |
| What the equation for net decline? | 0.5ˣ
> then you put your answer into a ratio.
x = the number of years the half life goes on for |
| What are the 3 equations for acceleration? | v² - u² = 2as
final velocity² - initial velocity² = 2 × acceleration × distance
m/s - m/s = 2 × m/s² × m
△v ÷ t = a
final - initial velocity ÷ time = acceleration
m/s ÷ s = m/s²
f ÷ m = a
force ÷ mass = acceleration
N ÷ kg = m/s² |
| What is Newtons Law 1? | The law of motion, inertia, it states that an object will stay at rest or in motion until another force acts on it. |
| What does inertia mean? | To remain unchanged. |
| What is Newtons Law 2? | It states that acceleration will be directly proportional to the force applied, and inversely proportional to its mass.
a ∝ f |
| What is Newtons Law 3? | It states that when two objects interact the forces that they exert on each other are equal and opposite. |
| What is terminal velocity? | When you don't speed up or slow down until another force acts upon you. |
| What is momentum? | A property of a moving object thats a vector quantity. |
| What is the equation for momentum? | p = m × v
momentum = mass × velocity
kg m/s = kg × m/s |
| A 1,800kg animal runs north at 9.5m/s. How much momentum does it have? | 1,800 × 9.5 = 17,100 kg m/s |
| A 40kg rock falls at 484 kg m/s. What is the velocity? | 484 = 40 × v
> 484 ÷ 40
= 12.1 m/s |
| What is the conservation of momentun? | The momentum before and after collision will be equal in a closed system (no external forces are acting upon it). |
| What is stopping distance? | The distance it takes for a vehicle to come to a complete stop. |
| What is the equation for stopping distance? | Thinking distance + Braking distance = Stopping distance
m + m = m |
| What is the thinking distance? | How far the vehicle travels during a drivers' reaction time. |
| What is the braking distance? | How far the vehicle travels after applying the brakes. |
| What factors can affect the thinking distance? | Speed and reaction time (tiredness, drugs, alcohol and distractions can affect your ability to react). |
| What factors can affect the braking distance? | Speed, weather, brake conditions, tire conditions (skidding), road conditions (wet or icy). |
| What do the brakes rely on to stop a vehicle? | Friction between the brakes and wheels.
The contact causes friction, causing work to be done.
The faster the vehicle goes, the more energy there is in its kinetic store, so more work must be done to stop it.
This means that a greater braking force is needed.
A larger braking force means a larger deceleration. This can be dangerous because it can cause the brakes to overheat, and make the vehicle skid. |
| A car is travelling at a typical speed and makes an emergency stop to avoid hitting a hazard 25m ahead. Estimate the braking force needed to produce this deceleratoin. | v² - u² = 2as
final velocity² - initial velocity² = 2 × acceleration × distance
v ≈ 25 m/s
m ≈ 1000 kg
a = (v² - u²) ÷ 2s
> (0² - 25²) ÷ (2 × 25) = -12.5
i)
F = ma
> F = 1000 × 12.5 = 12,500 N
So the force is ≈ 12,500 N |
